Iranian Journal of Electrical & Electronic Engineering http://ijeee.iust.ac.ir
Iranian Journal of Electrical and Electronic Engineering - Journal articles for year 2012, Volume 8, Number 2Yektaweb Collection - http://www.yektaweb.comen2012/6/12Two Novel Chaos-Based Algorithms for Image and Video Watermarkinghttp://ijeee.iust.ac.ir/browse.php?a_id=478&sid=1&slc_lang=en
In this paper we introduce two innovative image and video watermarking
algorithms. The paper’s main emphasis is on the use of chaotic maps to boost the
algorithms’ security and resistance against attacks. By encrypting the watermark
information in a one dimensional chaotic map, we make the extraction of watermark for
potential attackers very hard. In another approach, we select embedding positions by a two
dimensional chaotic map which enables us to satisfactorily distribute watermark
information throughout the host signal. This prevents concentration of watermark data in a
corner of the host signal which effectively saves it from being a target for attacks that
include cropping of the signal. The simulation results demonstrate that the proposed
schemes are quite resistant to many kinds of attacks which commonly threaten
watermarking algorithms.S. TalebiBilateral Weighted Fuzzy C-Means Clusteringhttp://ijeee.iust.ac.ir/browse.php?a_id=419&sid=1&slc_lang=en
Nowadays, the Fuzzy C-Means method has become one of the most popular
clustering methods based on minimization of a criterion function. However, the
performance of this clustering algorithm may be significantly degraded in the presence of
noise. This paper presents a robust clustering algorithm called Bilateral Weighted Fuzzy CMeans
(BWFCM). We used a new objective function that uses some kinds of weights for
reducing the effect of noises in clustering. Experimental results using, two artificial
datasets, five real datasets, viz., Iris, Cancer, Wine, Glass and a speech corpus used in a
GMM-based speaker identification task show that compared to three well-known clustering
algorithms, namely, the Fuzzy Possibilistic C-Means, Credibilistic Fuzzy C-Means and
Density Weighted Fuzzy C-Means, our approach is less sensitive to outliers and noises and
has an acceptable computational complexity.A. H. HadjahmadiDesign of a Photonic Bandgap Fiber with Optimized Parameters to Achieve Ultra-Low Confinement Losshttp://ijeee.iust.ac.ir/browse.php?a_id=356&sid=1&slc_lang=en
In this paper, a novel design of all-solid photonic bandgap fiber with ultra-low
confinement loss is proposed. The confinement loss is reduced remarkably by managing the
number of rods rings, up-doping level, pitch value, and rods diameters. Moreover, the
designed PCF shows ultra-flattened dispersion in L- and U-band. Furthermore, a new
design, based on introducing of an extra ring of air holes on the outside of the all-solid
bandgap structure, is then proposed and characterized. We demonstrate that it significantly
reduces the fiber diameter to achieve negligible confinement loss. The validation of the
proposed design is carried out by employing a two dimensional finite difference frequency
domain with perfectly matched layers.M. AliramezaniCancellation of Series-Loss Resistance in UWB Active Inductors using RC Feedbackhttp://ijeee.iust.ac.ir/browse.php?a_id=473&sid=1&slc_lang=en
One of the most important features of the Active Inductors (AIs) is their input
equivalent resistance, namely series-loss resistance, which should be low enough to have a
high Quality Factor (QF). Most of the previous methods by this goal did not yield a high
enough QF. This paper presents a new method, namely applying an RC feedback, to cancel
series-loss resistance entirely. As the RC feedback cancels series-loss resistance, it
enhances the Self-Resonant Frequency (SRF) as well. The SRF of the AI has a range as
high as 0.25-12.5 GHz. Compared to the previous reports, the QF has been improved by
applying the RC feedback. The structure is such that the QF can be adjusted independent of
the SRF. For example, a very high quality factor of 13159 at the frequency of 6.6 GHz with
a 2.2 nH inductance is obtained, while noise voltage and power dissipation are less than 4.6
nV Hz and 4 mW, respectively. The AI is designed and simulated using 90 nm CMOS
process and 1.2 V power supply. To the best of authors’ knowledge, this is the first time an
RC feedback has been implemented to cancel series-loss resistance.M. R. MosaviA Comparative Study on Predictive and ISVM Direct Torque Control Methods for a Doubly Fed Induction Machine Fed by an Indirect Matrix Converterhttp://ijeee.iust.ac.ir/browse.php?a_id=364&sid=1&slc_lang=en
This paper presents a comparative study on the Predictive Direct Torque Control
method and the Indirect Space Vector Modulation Direct Torque Control method for a
Doubly-Fed Induction Machine (DFIM) which its rotor is fed by an Indirect Matrix
Converter (IMC). In Conventional DTC technique, good transient and steady-state
performances are achieved but it presents a non constant switching frequency behavior and
non desirable torque ripples. However, in this paper by using the proposed methods, a fixed
switching frequency is obtained. In this model Doubly-Fed Induction Machine is connected
to the grid by the stator and the rotor is fed by an Indirect Matrix Converter. Functionally
this converter is very similar to the Direct Matrix Converter, but it has separate line and
load bridges. In the inverter stage, the Predictive method and ISVM method are employed.
In the rectifier stage, in order to reduce losses caused by snubber circuits, the rectifier fourstep
commutation method is employed. A comparative study between the Predictive DTC
and ISVM-DTC is performed by simulating these control systems in
MATLAB/SIMULINK software environments and the obtained results are presented and
verified.D. Arab KhaburiAutomatic Phase Advancing in a Stand-Alone Switched Reluctance Generator at Different High Speeds for Desired Output Voltagehttp://ijeee.iust.ac.ir/browse.php?a_id=422&sid=1&slc_lang=en
The switched reluctance motor is a singly excited, doubly salient machine which
can be used in generation mode by selecting the proper firing angles of the phases. Due to
its robustness, it has the potential and the ability to become one the generators to be used in
harsh environment. This paper presents an energy conversion by a Switched Reluctance
Generator (SRG) when bifilar converter circuit and discrete position sensors are employed.
As the generator’s speed increases by a prime mover the shape of current waveform
changes in such a way that limits the production of generating voltage. At high speeds, it is
possible for the phase current never reaches the desired value to produce enough back-emf
for sufficient voltage generation, therefore, the output power falls off. In order to remedy
this problem, the phase turn on angle is advanced in a way that the phase commutation
begins sooner. Since one of the advantages of this type of generator is its variable speed
then, the amount of advancing for the turn on angle should be accomplished automatically
to obtain the desired output voltage according to the speed of the generator, meaning, as the
generator speed increases so should the turn on angle and vice versa. In this respect, this
paper introduces an electronic circuit in conjunction with the position sensors and the drive
converter to achieve this task for a desired output voltage when a SRG feeding a resistive
load. To evaluate the generator performance, two types of analysis, namely numerical
technique and experimental studies have been utilized on a 6 by 4, 30 V, SRG. In the
numerical analysis, due to highly non-linear nature of the motor, a three dimensional finite
element analysis is employed, whereas in the experimental study, a proto-type generator
and its circuitries have been built and tested using bifilar converter. A linear analysis of the
current waveform for the generator under different advancements of the turn on angle has
been performed numerically and experimentally and the results are presented.E. AfjeiElectricity Procurement for Large Consumers with Second Order Stochastic Dominance Constraintshttp://ijeee.iust.ac.ir/browse.php?a_id=442&sid=1&slc_lang=en
This paper presents a decision making approach for mid-term scheduling of large
industrial consumers based on the recently introduced class of Stochastic Dominance (SD)-
constrained stochastic programming. In this study, the electricity price in the pool as well as
the rate of availability (unavailability) of the generating unit (forced outage rate) is
considered as uncertain parameters. The self-scheduling problem is formulated as a
stochastic programming problem with SSD constraints by generating appropriate scenarios
for pool price and self-generation unit's forced outage rate. Furthermore, while most
approaches optimize the cost subject to an assumed demand profile, our method enforces
the electricity consumption to follow an optimum profile for mid-term time scheduling, i.e.
three months (12 weeks), so that the total production will remain constant.M. ZarifStrategic Bidding in a Pool-Based Electricity Market under Load Forecast Uncertaintyhttp://ijeee.iust.ac.ir/browse.php?a_id=415&sid=1&slc_lang=en
This paper proposes a method for determining the price bidding strategies of
market participants consisting of Generation Companies (GENCOs) and Distribution
Companies (DISCOs) in a day-ahead electricity market, while taking into consideration the
load forecast uncertainty and demand response programs. The proposed algorithm tries to
find a Pareto optimal point for a risk neutral participant in the market. Because of the
complexity of the problem a stochastic method is used. In the proposed method, two
approaches are used simultaneously. First approach is Fuzzy Genetic Algorithm for finding
the best bidding strategies of market players, and another one is Mont-Carlo Method that
models the uncertainty of load in price determining algorithm. It is demonstrated that with
considering transmission flow constraints in the problem, load uncertainty can considerably
influences the profits of companies and so using the second part of the proposed algorithm
will be useful in such situation. It is also illustrated when there are no transmission flow
constraints, the effect of load uncertainty can be modeled without using a stochastic model.
The algorithm is finally tested on an 8 bus system.A. Akbari ForoudSolving Environmental/Economic Power Dispatch Problem by a Trust Region Based Augmented Lagrangian Methodhttp://ijeee.iust.ac.ir/browse.php?a_id=413&sid=1&slc_lang=en
This paper proposes a Trust-Region Based Augmented Method (TRALM) to
solve a combined Environmental and Economic Power Dispatch (EEPD) problem. The
EEPD problem is a multi-objective problem with competing and non-commensurable
objectives. The TRALM produces a set of non-dominated Pareto optimal solutions for the
problem. Fuzzy set theory is employed to extract a compromise non-dominated solution.
The proposed algorithm is applied to the standard IEEE 30 bus six-generator test system.
Comparison of TRALM results with the various algorithms, reported in the literature shows
that the solutions of the proposed algorithm are very accurate for the EEPD problem.H. Mohammadian BisheA Comparison Between Electrical Circuit and Finite Element Modeling Methods for Performance Analysis of a Three-Phase Induction Motor under Voltage Unbalancehttp://ijeee.iust.ac.ir/browse.php?a_id=426&sid=1&slc_lang=en
Induction motor is the most popular load in the industry, it is very important to
study about the effects of voltage quality on induction motor performance. One of the most
important voltage quality problems in power system is voltage unbalance. This paper
evaluates and compares two methods including finite element method (FEM) and
equivalent electrical circuit simulation for investigation of the effects of voltage unbalance
conditions on the performance of a three- phase induction motor. For this purpose, a threephase
squirrel cage induction motor is simulated using Finite Element Method and
equivalent electrical circuit parameters of the FEM model is estimated by genetic
algorithm. Then, some unbalanced voltages are applied on the FEM model of the Motor
and the resulted power and losses are compared with calculated values using equivalent
electrical circuit simulation in same voltage conditions.A. Ebadi